System and method for hydraulically managing fluid pressure downstream from a main valve between set points

ABSTRACT

A system for hydraulically managing fluid pressure between selected set points includes a pilot control system operably coupled to a main valve. The pilot control system includes at least one fluid conduit, a variable orifice assembly, and a control pilot valve apparatus. Fluid is passed through a fixed orifice and into a first chamber of the control pilot valve apparatus. Fluid is passed through the variable orifice of the variable orifice assembly and into a second chamber of the control pilot valve apparatus. The main valve is hydraulically opened or closed in response to a pressure differential between the first and second chambers of the control pilot valve apparatus so as to manage fluid pressure downstream of the main valve between the selected upper and lower set points.

BACKGROUND OF THE INVENTION

The present invention generally relates to automatic valves employed onmunicipal water utility systems. More particularly, the presentinvention relates to a hydraulically adjustable pressure managementcontrol valve designed to control downstream pressure between selectedset points.

There is a general understanding throughout the worldwide water supplyindustry that instances of water loss are common in many waterdistribution networks and in many instances the level of water loss canbe relatively high. The amount of water loss in the system is due to avariety of leak sources, such as improperly tightened pipe flangeconnections, leaking flange gaskets, leaking valve seals, failed seals,old pipes (with pinhole bursts), loose fittings, leaky faucets, etc. Thesum of these sources of leakage can add up to a substantial amount ofwater loss. Maintaining the entry point pressure at all times at thelevel necessary to provide adequate pressure at the distant points forperiods of high demand can result, during periods of low demand, inexcessive pressure at the consumer's premises, and thus increased wasteof water by unnecessary consumption and leakage. The volume of waterlost through leakage is directly related to pressure in the system.

Automatic pressure reducing valves are used in water distributionsystems to reduce pressure to a pre-determined value or sub-point thatis adequate, but does not expose normal components, such as householdhot water tanks, to overpressure. The sub-point is typically determinedto provide minimum pressure that meets criteria of the water utility,particularly under maximum or “peak” demand conditions which can occurwhen a fire is being fought. The pressure required for peak demand isusually significantly higher than that required for “off-peak” ortypical nighttime conditions. Under low demand conditions, not only doesleakage form a higher proportion of the total demand, but investigationhas implied that some leak orifices can actually increase in area withpressure, aggravating the problem if excessive pressures are maintainedat all times.

Various attempts have been previously made to reduce such losses byintroducing a degree of control over the supply pressure in response todemand. One known system uses electrical circuit means with pressure andflow-rate sensors from monitoring pressure and flow-rate and thenprocessing the information obtained and using it in turn to controlsuitable electrically operated valve means. Such systems are, however,relatively complex and expensive and require a continuous external powersupply giving rise to additional capital and running costs andreliability problems.

There also exist flow-driven valves which use fluid pressures to controlactuation of the main valve, and thus are independent of external powersources and can be used in essentially any location. One suchflow-driven valve system is disclosed in U.S. Pat. No. 5,967,176 toBlann, et al. The system controls high and low pressures by utilizingthe pressure drop across an orifice plate that is installed in the mainline, usually attached directly to the inlet or outlet flange of themain valve. The pressure control is independent of the main valveposition, and is a direct function of system flow. The pressure controldevice monitors the pressure drop or flow across the orifice plate.Control pressure is varied based upon the movement of a pilot valvemember with respect to a fixed pilot valve member, which in turncontrols the main control valve.

However, this system has many shortcomings. The diameter of the orificeplate may need to be customized for different high/low flowapplications. For example, a smaller orifice diameter may be required ifflows are not sufficient to develop the required pressure drop acrossthe system orifice. Likewise, the system orifice may need to beincreased if pressure drops are too large because a smaller orifice canlimit the flow capacity of the system. The orifice plate also decreasesthe capacity of the main valve. This is particularly a concern when highflow is necessary, such as a high flow of water to fight a fire or thelike. The added orifice plate limits the capacity of the main valve forfire flow situations. Moreover, it is difficult to retrofit existingvalves with this system as the flange spacing must be modified toaccommodate the orifice plate, typically requiring removal of the mainvalve from the line.

Accordingly, there is a continuing need for an improved flow-drivenvalve system for automatically controlling downstream pressure betweenselected set points. The present invention fulfills these needs andprovides other related advantages.

SUMMARY OF THE INVENTION

The present invention resides in a system and method for hydraulicallymanaging fluid pressure between selected set points. As will be morefully described herein, the system is flow-driven and responds tochanging flow demand downstream from a main valve, so as to manage andcontrol the fluid pressure downstream from the main valve betweenpredetermined set points.

The system generally comprises a main valve having a main valve bodydefining a fluid inlet and a fluid outlet. A main valve seat is disposedbetween the fluid inlet and the fluid outlet. A main valve member ismovable between an open position away from the main valve seat, and aclosed position engaging the main valve seat. The main valve isconfigured to hydraulically open to increase fluid flow therethrough,and hydraulically close to reduce fluid flow therethrough. A main valvediaphragm is coupled to the main valve member. The main valve diaphragmand the main valve body, or a cover thereof, define a control chamberhaving a control port in fluid communication with a pilot controlsystem.

The pilot control system is operably coupled to the main valve and hasat least one fluid conduit for passing fluid through a fixed orifice andinto a first chamber of a control pilot valve apparatus, and for passingfluid through a variable orifice assembly defining a variable orificeand into a second chamber of the control pilot valve apparatus.

The variable orifice assembly comprises a housing associated with thevalve, and defines a fluid inlet and outlet. A stem is connected to thevalve member and slidably disposed within the housing. Movement of thestem within the housing creates a variable fluid orifice between thefluid inlet and the fluid outlet of the housing.

The variable orifice assembly stem may include a fluid inlet in fluidcommunication with the fluid inlet of the housing, and a fluid outletvariably in fluid communication with the fluid outlet of the housing asthe stem is moved. In another embodiment, a sleeve is disposed betweenthe housing and the stem. The sleeve has an aperture in fluidcommunication with the housing fluid outlet. The stem is adapted tovariably permit fluid to pass from the housing fluid inlet to the sleeveaperture, and the housing fluid outlet. Preferably, the sleeve isadjustably positioned within the housing to vary the fluid flow from thehousing fluid inlet to the housing fluid outlet.

At least one fluid conduit includes a first inlet disposed upstream ofthe main valve seat and in fluid communication with the fixed orificeand the variable orifice assembly. A second inlet is disposed downstreamof the main valve seat, the second inlet being in fluid communicationwith the first chamber of the control pilot valve apparatus.

A pressure regulator apparatus may be disposed between the fluid conduitinlet and the fluid inlet of the variable orifice assembly to customizeand regulate the pressure entering into the variable orifice assembly.The pressure regulator comprises a housing having a fluid inlet and afluid outlet. A selectively adjustable fluid passageway is disposedbetween the fluid inlet and fluid outlet.

The control pilot valve apparatus generally comprises a housing having afirst flexible diaphragm disposed therein and defining a first variablechamber above the first flexible diaphragm. The first variable chamberhas a fluid inlet and a fluid outlet. A movable yoke is attached to thefirst flexible diaphragm. A second flexible diaphragm is disposed withinthe housing in spaced relation to the first flexible diaphragm, anddefines a second variable chamber below the second flexible diaphragm.The second variable chamber has a fluid inlet. A stem is attached to thesecond flexible diaphragm and slidably disposed relative to the yoke.The yoke and stem cooperatively form a variable fluid passageway betweenthe inlet and the outlet of the first variable chamber.

Typically, the stem includes an aperture variably alignable with a yokeaperture such that as the yoke and stem move relative to one another,they cooperatively define the variable fluid passageway.

The movement of the stem is limited to a selected range defining a lowerpressure set point. Typically, such means includes an adjustable springassembly for adjusting the movement of the stem to the selected rangedefining the lower pressure set point. Similarly, the movement of theyoke is limited to a selected range so as to define an upper pressureset point. Typically, such means includes an adjustable spring assemblyfor adjusting the movement of the yoke to the selected range definingthe upper pressure set point.

The pilot control system hydraulically opens or closes the main valve inresponse to a pressure differential between the first and secondchambers of the control pilot valve apparatus, so as to manage fluidpressure downstream of the main valve between the selected upper andlower set points.

A method of controlling fluid flow through a main valve to maintaindownstream pressure between pre-determined set points in accordance withthe present invention comprises the steps of generating a fluid streamhaving a pressure proportional to an inlet pressure of the main valve. Afirst portion of the fluid stream is passed through a fixed orifice andinto the first chamber of the control pilot valve apparatus above theflexible diaphragm thereof. A second portion of the fluid stream ispassed through the variable orifice assembly and into the second chamberof the control pilot valve apparatus below the flexible diaphragm. Apressure differential between the first and second chambers of thecontrol pilot valve apparatus is detected, resulting in the hydraulicopening or closing of the main valve by transmitting a fluid stream intothe control chamber of the main valve. The fluid passageway of thevariable orifice is automatically altered in response to the opening andclosing of the main valve.

The second portion of the fluid stream may be passed through thepressure regulator passageway before passing the second portion of thefluid stream through the variable orifice. The pressure regulatorpassageway may be adjusted in order to modify a pressure regulationprofile.

A lower pressure set point is set by selectively limiting a range oftravel of the flexible diaphragm of the control pilot valve apparatus.An upper pressure set point is set by selectively limiting a range oftravel of a second, or upper, flexible diaphragm of the control pilotvalve apparatus which is disposed above the first chamber.

A second fluid stream is generated which has a pressure proportional toan outlet of the main valve. This second fluid stream is placed in fluidcommunication with the first chamber of the control pilot valveapparatus.

Other features and advantages of the present invention will becomeapparent from the following more detailed description, taken inconjunction with the accompanying drawings, which illustrate, by way ofexample, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a schematic illustration of a system in a high fluid flowstate for hydraulically managing fluid pressure downstream of a mainvalve between selected set points, in accordance with the presentinvention;

FIG. 2 is a cross-sectional view of a main valve and a variable orificeassembly positioned in a high flow state, in accordance with the presentinvention;

FIG. 3 is an enlarged cross-sectional view of area “3” of FIG. 2,illustrating a variable orifice thereof in an open position;

FIG. 4 is a cross-sectional view of an alternative variable orificeassembly embodying the present invention;

FIG. 5 is an enlarged cross-sectional view taken generally along area“5” of FIG. 4, illustrating the variable orifice in an open position;

FIG. 6 is a cross-sectional view of a control pilot valve apparatus usedin accordance with the present invention, in a high flow state;

FIG. 7 is a cross-sectional view of a pressure regulator apparatus usedin accordance with the present invention;

FIG. 8 is a diagram illustrating pressure profiles created by modifyingthe variable orifice assembly and implementing the pressure regulatorapparatus;

FIG. 9 is a cross-sectional view of the control pilot valve apparatus ina high pressure state;

FIG. 10 is a schematic illustration of the system of the presentinvention in a low flow state;

FIG. 11 is a cross-sectional view of the main valve and variable orificeassembly in the low flow state;

FIG. 12 is an enlarged cross-sectional view of area “12” of FIG. 11,illustrating a variable orifice thereof in a closed position;

FIG. 13 is a cross-sectional view of the variable orifice assembly ofFIG. 4, but illustrating the variable orifice in a closed position;

FIG. 14 is an enlarged cross-sectional view of area “14” of FIG. 1 3;

FIG. 15 is a cross-sectional view similar to FIG. 13, but illustrating asleeve thereof moved into a different profile position; and

FIG. 16 is a cross-sectional view of the control pilot valve apparatusused in accordance with the present invention in a low flow state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the accompanying drawings, for purposes of illustration, thepresent invention is directed to an adjustable hydraulically operatedpressure management control valve system 10. As will be more fullydescribed herein, the system 10 of the present invention is primarilyintended for use in the waterworks industry where there is a desire toreduce the amount of water loss in the system due to leaks. Theinvention can reduce the amount of water loss in a system by reducingthe system pressure as the flow or system demand decreases. A commonexample would be a residential water system where water demand is highduring the day and low at night. If the pressure is lower during lowusage, then a lower pressure will result in lower water lossesthroughout the system.

As will be more fully described herein, the system 10 of the presentinvention comprises a main valve assembly 100 operably coupled to apilot control system 20. The pilot control system 20 includes a variableorifice assembly 200, a control pilot valve apparatus 300, and anoptional pressure regulator apparatus 400. Various conduits 22-42fluidly couple these components and provide pressurized fluid streams,as will be more fully described herein. The pilot control system 20hydraulically opens the main valve assembly 100 during high demandconditions, and closes the main valve assembly 100 during low demandconditions, resulting in a reduction of the amount of water loss in awaterworks system downstream of the main valve assembly 100.

With reference now to FIGS. 1 and 2, the main valve 100 is comprised ofa main valve body 102 defining an inlet 104 and an outlet 106.Intermediate the main valve inlet and outlet 104 and 106 is a main valveseat 108. A main valve member is movable between an open position awayfrom the main valve seat 108, as illustrated in FIG. 1, and a closedposition engaging the main valve seat 108. The main valve member 110includes a movable stem 112 for guiding the main valve member 110 intoand out of engagement with the main valve seat 108. A spring 114 istypically also implemented in facilitating and guiding the main valvemember 110 movement. A main valve diaphragm 116 is coupled to the mainvalve member 110 and extends between the main valve body 102 and a cover118 of the main valve 100 so as to define a fluid control chamber 120between the diaphragm 116 and the cover 118, or other portion of thebody 102. The control chamber includes an inlet port 122 for fluidcoupling with the pilot control system 20, such as through conduit 32.

As will be more fully explained herein, the pilot control system 20increases fluid flow into the control chamber 120 during low flow or lowdemand situations, causing the main valve member 110 to move downwardlytowards engagement with the main valve seat 108. Conversely, during highflow or high demand situations, less fluid is directed into the fluidcontrol chamber 120, resulting in a lower pressure and enabling the mainvalve member 110 to move away from the main valve seat 108 into an openposition so as to permit more fluid to flow through the main valve 100.

With reference again to FIG. 1, conduit 22 has an inlet 24 disposedupstream of the main valve seat 108 and main valve member 110, typicallyadjacent to the inlet 104 of the main valve assembly 100. A fluid streamhaving a pressure proportional to the fluid stream at the inlet 104 ofthe main valve 100 is generated. A portion of the fluid stream isdiverted into conduit 26 and through the variable orifice assembly 200.As will be more fully described below, the portion of the fluid streampassing through conduit 26 may first pass through a pressure regulatordevice 400 so as to control the profile of the pressure regulation rampand maintain pressure stability to the inlet 200 when regulating betweenlow and high pressure set points.

With reference now to FIG. 2, in one embodiment the variable orificeassembly 200 includes a housing 202 defining a fluid inlet 204 and afluid outlet 206. Typically, the housing 202 is coupled to the mainvalve cover 118, as illustrated. However, fluid pressures within thevariable orifice assembly housing 200 and the main valve 100 areisolated from one another, such as by utilizing an O-ring 208 in anadapter 210 which isolate the pressure within the housing 202 and themain valve control chamber 120.

A stem 212 is movably disposed within the housing 202, and coupled tothe stem 112 of the main valve member 110. In this manner, as the mainvalve member 110 moves up and down, the stem 212 of the variable orificeassembly 200 also moves up and down. The housing 202 and the stem 212cooperatively define a variable orifice 214. For example, typically thestem 212 is at least partially hollow and includes an aperture or slittherein. As illustrated in FIG. 3, when the stem 212 is raised upwardly,the variable orifice 214 is in fluid communication with the outlet 206,such as by an intermediate chamber 216.

With reference now to FIG. 4, an alternative variable orifice assembly200′ is shown which is capable of being adjusted so as to customize apressure regulation curve, between set points, to set the applicationpreferences of the user. In this embodiment, the assembly 200′ alsoincludes a housing 202′ which is connected to the main valve member,typically the cover member 118, such as by threaded connection 201′. Astem 212′ is connected to the main valve member stem 112, as discussedabove, and includes an adapter 210′ with an O-ring 208′ to create aleak-free connection so as to separate pressures therebetween. Thehousing 202′ includes a fluid inlet 204′ and a fluid outlet 206′.

In this case, however, the stem is not hollow. Instead, the housing 202′is adapted so as to receive a sleeve 203′ between the inner wall of thehousing 202′ and the stem 212′. As illustrated in FIGS. 4 and 5, thesleeve 203′ includes an aperture, typically in the form of a slit 205′,which is in fluid communication with an intermediate chamber 216′ of thehousing 202′, which is in fluid communication with the outlet 206′. Asection 207′ of the stem is configured so as to have a greater diametertowards an upper portion thereof, or a shoulder which may include anO-ring or the like, and be of reduced diameter, or include externalpassageways or the like, in a lower portion thereof such that when thestem 212′ is raised sufficiently, the reduced diameter profile of thesection 207′ is in alignment with the slot 205′ of the sleeve 203′,permitting fluid to flow from the housing inlet 204′, around the stemsection 207′, through the sleeve slot 205′, into the intermediarychamber 216′, and out outlet 206′.

It will be readily appreciated by those skilled in the art that the slot205′ can be created so as to create a pressure regulation profile byincreasing or decreasing the fluid flow therethrough. Similarly, theexterior configuration of the stem section 207′ can be modified tocorrelate to increased or decreased fluid flow. However, thesetechniques do not allow adjustment after the assembly 200′ has beenmanufactured and assembled.

Thus, with reference to FIGS. 4, 5 and 13, the sleeve 203′ is adjustablyinserted and connected to the housing 202′, such as by threadedconnection between the internal threads 209′ and external threads 211′of the housing 202′ and sleeve 203′, respectively. This allows thesleeve 203′ to be raised or lowered, thus adjusting the position of thesleeve slot 205′, and thus requiring a greater or lesser stroke of themain valve stem 112 so as to open or close the variable orifice betweenthe variable orifice assembly inlet 204′ and outlet 206′.

The travel of the sleeve 203′ may be limited, for example, by the use ofa set screw 213′ which is disposed above a shoulder 21 5′ of the sleeve203′. Also, this serves as a precautionary feature so as to not permitthe user to inadvertently unthread the sleeve 203′ to the point wherethe variable orifice assembly 200′ does not function. It will beappreciated that the adjusting position of the sleeve aperture 205′ canbe used to change or customize the pressure curve profile between thelow and high flow set points of the system.

With reference again to FIG. 1, when the stem 212 of the variableorifice assembly 200 is raised so as to open the variable orifice andpermit fluid to flow therethrough, the fluid passes into conduit 34 andis split such that a portion of the fluid is passed through a fixedorifice device 50 through conduit 38 which is fluidly coupled to thecontrol pilot valve apparatus 300, and another portion is passed throughconduit 36 and into the control pilot valve apparatus 300.

More particularly, with reference to FIG. 6, the control pilot valveapparatus 300 includes an inlet port 302, fluidly coupled to conduit 36,leading to a lower, or second, chamber 304 thereof. A flexible diaphragm306 extends across the housing 308 and divides the lower chamber 304from an upper chamber 310. As will be more fully described herein, it isthe pressure differential between the first, or upper, chamber 310 andthe second, or lower, chamber 304 which results in the hydraulic openingand closing of the main valve 100.

The control pilot valve apparatus 300 includes a low pressure adjustmentscrew 312 threadedly connected to an end member 314 and having a stopnut 316 threadedly attached thereto. The end of the screw 312 engages aguide 318, supporting a spring 320. The spring is contained within apiston 322 such that the spring 320 exerts a force on the piston 322.

A stem 324 is connected to the piston 322, such as by use of a nut 326and a threaded end of the stem 324 extending into the body of the piston322. The stem 324 also extends through the diaphragm 306 and a washer328 disposed on a top surface of the diaphragm 306. An upper nut 330 maybe threaded onto the stem 324, or a shoulder formed in the stem. Thelower and upper nuts 326 and 330 sandwich and couple the piston 322, thediaphragm 306, the stem 324, and the washer 328 to one another. Thus, ifany of these components are moved, such as due to the force of thespring 320 or the fluid pressure in chamber 304, the connected membersalso move. An upper portion of the stem 324 is hollow, and includes anaperture or slot 332 therein.

A high pressure adjustment screw 334 threadedly extends through an uppermember 336 of the body and includes a stop nut 338. The end of the highpressure adjustment screw 334 is in contact with an upper spring guide340 which acts upon an upper spring 342. The spring 342 extends betweenthe upper guide 340 and a washer 344 coupled to an upper, and typicallysmaller, diaphragm 346. The upper diaphragm 346 is disposed above theupper or first chamber 310, and a chamber 348 having atmosphericpressure.

A yoke 350 has a threaded end 352 with a nut 354 which couples the yoke350 to the upper diaphragm 346 and washer 344. The yoke 350 includes apassageway or opening 356. The yoke passageway 356 and the stem slot 332are alignable with one another so as to permit fluid to flow through aninlet 358 of the control pilot valve apparatus and into the firstchamber 310, and out an outlet 360. The stem 324 and the yoke 350 areslidably nested or otherwise arranged so that they independently move,yet cooperatively define a variable fluid passageway between the inlet358 and outlet 360. It will be appreciated that depending upon theposition of the stem 324 and the yoke 350, the stem slot 332 and yokeaperture 356 are either completely aligned with one another, partiallyaligned with one another so as to restrict flow therethrough, orcompletely non-aligned so as to prevent fluid flow into and through thefirst upper chamber 310 of the control pilot valve apparatus 300.

Typically, a coupling member or stem guide 362 has an orifice orpassageway therethrough 364 to permit fluid flow between an upperportion of the first chamber 310 adjacent to the inlet and outlet 358and 360, and a lower portion of the upper or first chamber 310immediately above the lower diaphragm 306. Thus, fluid pressure in theupper or first chamber 310 can act upon both the lower diaphragm 306 andthe upper diaphragm 346 of the control pilot valve apparatus 300.

With reference again to FIG. 1, a high demand or high flow situation isillustrated. A fluid stream is generated through inlet 24, and passedthrough conduit 22. A portion of the stream is passed through conduit28, through fixed orifice device 52. From there, this portion of thestream is fluidly coupled through conduits 30 and 32 to the inlet 358 ofthe control pilot valve apparatus 300 and the control chamber 120 of themain valve 100. Another portion of the fluid stream is directed throughconduit 26 and into the inlet port 204 of the variable orifice assembly200. In the high flow/high demand situation, the main valve seat 110 isopened and moved away from the valve seat 108. Thus, as the stem 112 ofthe main valve 100 is moved upwardly, the stem 212 of the variableorifice assembly 200 is moved as well, exposing to an increasing levelthe variable orifice 214 until the variable orifice 214 presents amaximum passageway for fluid to flow therethrough, out outlet 206, andinto conduit 34.

The fluid stream in conduit 34 is split between conduits 36 and 38. Thefluid stream in conduit 38 passes through a fixed orifice device 50, andis fluidly coupled to the outlet 360 of the control pilot valveapparatus 300. The fluid stream in conduit 36 is passed through inlet302, and into the lower, or second chamber 304. As the variable orifice214 is presented at its maximum flow, the amount of fluid stream, andthus fluid pressure, entering into the chamber 304 is relatively large,causing the lower diaphragm 306 to move upwardly, as illustrated inFIGS. 1 and 6. The diaphragm 306 can move up to a point wherein thewasher 328 comes into contact with the guide or coupler 362.

As the lower diaphragm 306 moves upwardly, the aperture or slot 332 inthe stem 324 is moved upwardly so as to become increasingly aligned withthe corresponding aperture or slot 356 of the yoke 350. Thus, the fluidin conduit 30 is able to pass through the inlet 358, and through thealigned apertures or slots 332 and 356 of the stem 324 and yoke 350, andinto the upper or first chamber 310. The fluid is also able to exitoutlet 360 of the control pilot valve apparatus, and into conduit 40.Due to the relatively free flow of the fluid, as described above, arelatively lesser amount of fluid and fluid pressure is introduced intothe control chamber 120 of the main valve 100, permitting the main valvemember 110 to be moved upwardly towards the main valve cover 118. Itwill be noted that in this situation, the pressure at P2 is greater thanthe pressure at P3 at the other side of fixed orifice device 50. This isdue to a relatively high flow of fluid through variable orifice 214 andinto the lower chamber 304 of the control pilot valve apparatus 300.Moreover, there is a pressure differential between the lower chamber 304and the upper chamber 310, causing the diaphragm 306 to move upwardly,aligning slots 332 and 356, resulting in the hydraulic opening of themain valve member 110. Such would be the case, for example, when a largeflow is required downstream from the main valve assembly 100.

As explained above, the design of the present invention controls highand low pressures by interacting with the variable orifice 214 or thevariable orifice assembly 200 operably coupled to the main valveassembly 100. The variable orifice 214 opening increases or decreaseswith the main valve member 110 stroke upwardly or downwardly. Thevariable orifice 214 interacts with the fixed orifice 50 in the controlpilot system 20. As system demand increases, the main valve 100 opens torespond to the increased system demand. As the main valve 100 opens, theflow area through the variable orifice 214 increases, which in turnincreases the pressure drop, or pressure differential, across the fixedorifice device 50. The pressure drop, or differential, across this fixedorifice 50 is used to control the transition of system downstreampressure between the low and high pressure set points of the controlpilot valve apparatus 300.

In the illustrated design, the low pressure set point is set andadjusted by turning screw 312, which serves to compress or decompressspring 320, thus limiting the range of motion or travel of the lowerdiaphragm 306 and stem 324. The upper or high pressure adjustment ismade by selectively turning screw 334, thus compressing or decompressingspring 342, and thus affecting the range of travel of the upperdiaphragm 346 and the yoke 350. Such adjustments set the low and highpressure set points of the system 10.

The variable orifice 214 can be customized to control the rate of changebetween the low and high pressure settings. If the flow area through thevariable orifice 214 is profiled to increase quickly (relative to mainvalve member 110 stroke), the transition between low and high pressureset points will likewise change quickly. For example, for a variableorifice 214 where the flow area through the variable orifice quicklychanges, the transition between the low pressure set point and the highpressure set point would occur fairly quickly between the low and highflow conditions resulting in a relatively steep curve between the lowand high set points. For instance, for a given valve size, such as aneight-inch valve, pressure change could occur within a two hundredgallon-per-minute flow span, or a relatively steep curve. However, ifthe flow area through the variable orifice 214 is profiled to increaseslowly, relative to main valve member 110 stroke, then the transitionbetween the low and high pressure set points will likewise changeslowly. For example, a variable orifice 214 where the flow area throughthe variable orifice slowly changes, then the same low-high pressuretransition would occur fairly slowly between the low and high flowconditions. In this case, the change might occur within a five hundredgallon-per-minute flow span, or a relatively shallow curve. Changing thevariable flow area geometry of the variable orifice 214 can be used tochange or customize the pressure curve profile between the low and highflow set points.

With reference now to FIGS. 1 and 7, as mentioned above, fluid streamthrough conduit 26 may be passed through pressure regulator apparatus400 before being passed into the variable orifice assembly 200. Thepressure regulator apparatus 400 is another means of customizing andcontrolling the rate of change between the low and high pressuresettings, so as to change or customize the pressure curve profilebetween the low and high flow set points. The pressure regulatorapparatus generally comprises a plug 402 connected to a seat assembly orbody 404, and supporting a disc retainer assembly 406. The body 404defines an inlet 408 and an outlet 410. A chamber or passageway 412 isdisposed between the inlet and outlet 408 and 410. A cover or upper body414 defines a chamber 416, typically exposed to atmosphere. A diaphragm418 is disposed between chambers 412 and 416. The diaphragm 418 isoperably connected or coupled to a spring 420 and a yoke 422. A portionof the yoke defines a passageway 424 alignable with a passageway of theinlet 408, so as to permit fluid to flow therethrough. However,depending upon the position of the yoke 422, the fluid is either allowedto pass through into passageway or chamber 412, and out outlet 410, oris restricted or even closed from passing into passageway or chamber412.

The set point or adjustment is made by a screw 426 being turnedclockwise or counterclockwise, which applies a force to spring guide428, causing the spring 420 to be compressed or relaxed. This impactsthe position of diaphragm 418, and yoke 422. This also establishes arange of travel for the diaphragm 418, if any, so as to produce arelatively constant flow or pressure through outlet 410, represented byP1 in FIG. 1. The pressure regulator device 400 is used to control thepressure at P1. This in turn customizes the profile of a pressureregulation ramp when regulating between low and high pressure setpoints. When pressure at P1 is equal to, or nearly equal to, thepressure at the main valve inlet 104, then the pressure ramp is at itssteepest. When the pressure at P1 is appreciably lower than the mainvalve inlet 104 pressure, then the pressure ramp is shallower.

With reference now to FIG. 8, a diagram illustrates the downstreampressure as compared to flow through the main valve 100. Thus, when theP1 pressure equals the main valve inlet pressure 104, a relatively steepcurve, shown by the solid line results. When the pressure at P1 is lessthan the main valve inlet 104 pressure, illustrated by the dotted lines,a shallower curve or profile is created. This occurs due to the use ofthe pressure regulator apparatus 400. In FIG. 8, a pressure profile isillustrated wherein the variable orifice 214 is modified (illustrated bythe dashed line). Including both the pressure regulator apparatus 400 aswell as modifying the variable orifice 214 results in a relativelyshallow profile, illustrated by the elongated dashed line.

Referring now to FIGS. 1 and 9, at some point during the high flow orhigh demand situation, the pressure at P3 will begin to increase, due tothe pressure of the stream generated at inlet 42, and passed throughconduit 40. In such a case, the pressure in upper chamber 310 of thecontrol pilot valve apparatus 300 will begin to increase.

As the pressure in the first chamber 310 begins to increase, upperdiaphragm 346 will be forced to move upwardly, pulling yoke 350 upwardlywith it, and constricting the passageway through slots or apertures 332and 356. In fact, when diaphragm 346 is moved to its upper mostposition, the yoke 350 may be sufficiently raised so that its apertureor slot 356 is no longer aligned whatsoever with the slot or aperture332 of the stem 324, such that fluid is not allowed to passtherethrough. Such is illustrated in FIG. 9.

As described above, adjustment screw 334 is rotated so as to relax orcompress spring 342, increasing or decreasing the range of potentialmotion and travel of the diaphragm 346 and the yoke 350. In this manner,the high pressure set point can be adjusted and set to a predeterminedlevel.

With reference now to FIG. 10, when the pressure within the upper orfirst chamber 310 of the control pilot valve apparatus 300 is sufficientso as to reach the high pressure set point, as described above, backfluid flow and pressure will build up in conduits 30 and 32, causing anincrease in fluid flow and pressure into the inlet port 122 and controlchamber 120 of the main valve assembly 100, preventing the main valvemember 110 from moving upwardly to any greater extent, or building upsufficient pressure within the control chamber 120 so as to push thediaphragm 116, and thus the main valve member 110, downwardly towardsseat 108. This reduces the flow through the main valve 100, and reducesthe downstream pressure such that it is below the high pressure setpoint.

With continuing reference to FIG. 10, the system 10 is illustrated in alow flow or low demand state, wherein the main valve member 110 is movedtowards the main valve seat 108, so that fluid flow through the mainvalve 100 is restricted, or there is a relatively low flow through themain valve assembly 100.

With reference now to FIG. 11, in such a low flow or low demandsituation, the main valve member 110 moves towards its closed positionadjacent to main valve seat 108. Thus, variable orifice assembly stem212 is moved downwardly, occluding variable passage 214, limiting orrestricting, or even preventing, fluid flow therethrough and out outlet206. This can be seen in FIG. 12.

With reference now to FIGS. 13-15, in the alternative embodiment of thevariable orifice assembly 200′, when the stem 212′ is moved downwardly,section 207′ is moved downwardly as well, such that the wider diameterportion of the section 207′ is in contact with the sleeve 203′, eitherreducing or preventing fluid flow from the assembly inlet 204′ and thesleeve slot 205′, and thus outlet 206′. It will be noted that the sleeve203′ has been adjustably moved when comparing the variable valve orificeassembly 200′ illustrated in FIGS. 13 and 15. As discussed above,movement of the sleeve 203′, either into or out of the housing 202′,adjusts the position of the sleeve slot 205′, and thus impacts theresulting fluid flow profile. However, in both FIGS. 13 and 15, the stem212′ has been moved downwardly sufficiently that there is little, ifany, fluid flow from the housing inlet 204′ to the outlet 206′.

This results in a lower fluid flow and pressure at P2, and lower chamber304 of the control pilot valve apparatus 300. The lower pressure inchamber 304 naturally biases the lower diaphragm 306 downwardly, as canbe seen in FIG. 16. This causes the stem 324 to move downwardly, movingthe slot 332 thereof out of alignment with the yoke opening 356. Thisrestricts, or even prevents in some cases, fluid entering inlet 358 frompassing into upper chamber 310, and out outlet 360. This causes a backpressure, which increases in control chamber 120 of the main valveassembly 100, preventing the main valve member 110 from moving upwardly,or if sufficient pressure is present in control chamber 120, moving themain valve member 110 downwardly toward seat 108 to restrict the flow offluid through the main valve 100. Moreover, the reduction in pressure inupper chamber 310 cause the upper diaphragm 346 to either remain inposition, or move downwardly, as illustrated in FIG. 11, depending uponthe pressure in chamber 310.

The passage area through the variable orifice 214 changes with thechange in the main valve member 110 position. Main valve number 110position changes in response to system flow demand conditions, openingas demand increases and closing as demand decreases. Restricted flowthrough the variable orifice 214 causes a low pressure drop, or pressuredifferential, through the fixed orifice 50, which causes restricted flowthrough the control pilot valve apparatus 300. This action causes themain valve 100 to throttle closed towards a lower pressure set point.The lower pressure set point is established by adjusting set screw 312,which compresses or relaxes spring 320, directly affecting the range oftravel and motion of lower diaphragm 306.

However, when system flow demand increases, the main valve 100 respondsby opening, which increases flow area through the variable orifice 214,as described above. Increased flow through the variable orifice 214increases the pressure drop, or differential, across fixed orifice 50.This action causes the main valve 100 to throttle open towards thehigher set point.

Due to the varying flow of fluid through the variable orifice 214, thepressure acting on the lower diaphragm 306 also varies. When thepressure on the top of the lower diaphragm, in chamber 310, is equal toor slightly higher than the pressure under the lower diaphragm, inchamber 304, then hydraulic forces bias the travel of the slotted stem324 in a direction that reduces the flow area through the slot 332. Thisaction, as described above, causes the main valve 100 to throttletowards the low pressure, or low flow, set point.

However, as pressure under the lower diaphragm in chamber 304 increasesrelative to pressure above the lower diaphragm 306 in chamber 310, thenhydraulic forces bias the travel of the slotted stem 324 in a directionthat increases the flow area through the slot 332. This action causesthe main valve 100 to throttle towards the high pressure, or high flow,set point. As described above, when the pressure in the upper chamber310 is sufficiently great, the upper diaphragm 346 moves upwardly to itsselected high pressure set point, moving the yoke upwardly, andrestricting the flow through the slot 332 and yoke passageway 356,increasing the pressure in the control chamber 120, and eitherpreventing the main valve member 110 from moving upwardly any further,or forcing the main valve member 110 downwardly towards a more closedposition. In all flow conditions (low and high) the stem 324 and yoke350 are independently moved and do not interfere with one another'stravel. The exposed slot area, or variable passageway, through thecontrol pilot valve apparatus 300 varies with changing system conditionscausing flow to modulate. This arrangement allows the main valve 100 tomodulate between the pre-selected high and low pressure set pointsestablished at the control pilot valve apparatus 300, as describedabove. More particularly, it is the selection of the springs 320 and 342acting on the lower and upper diaphragms 306 and 346 which create thehigh and low pressure set points. The low pressure set point isdetermined by the applied force of the lower spring 320. Decreasing thespring force of the lower spring 320 lowers the downstream pressure.Increasing the spring force of the upper spring 342 raises thedownstream pressure. The upper spring 342 is used to set the systempressure for normal or high flow conditions, while the lower spring 320is used to set the system pressure conditions for low flow conditions.

Although several embodiments have been described in some detail forpurposes of illustration, various modifications may be made withoutdeparting from the scope and spirit of the invention. Accordingly, theinvention is not to be limited, except as by the appended claims.

1. A system for hydraulically managing fluid pressure between selectedset points, comprising: a main valve having a fluid inlet and a fluidoutlet, the main valve being configured to hydraulically open toincrease fluid flow therethrough, and hydraulically close to reducefluid flow therethrough; and a pilot control system operably coupled tothe main valve and having at least one fluid conduit for passing fluidthrough a fixed orifice and into a first chamber of a control pilotvalve apparatus, and for passing fluid through a variable orificeassembly defining a variable orifice and into a second chamber of thecontrol pilot valve apparatus, whereby the pilot control systemhydraulically opens or closes the main valve in response to a pressuredifferential between the first and second chambers of the control pilotvalve apparatus so as to manage fluid pressure downstream of the mainvalve between selected upper and lower set points.
 2. The system ofclaim 1, wherein the main valve comprises a main valve body defining thefluid inlet and the fluid outlet, a main valve seat disposed between thefluid inlet and the fluid outlet, a main valve member movable between anopen position away from the main valve seat and a closed positionengaging the main valve seat, and a main valve diaphragm coupled to themain valve member, the main valve diaphragm and the main valve body, ora cover thereof, defining a control chamber having a control port influid communication with the pilot control system.
 3. The system ofclaim 2, wherein the variable orifice assembly comprises a housingassociated with the main valve, the housing having a fluid inlet and afluid outlet, and a stem slidably disposed within the housing andcoupled to the main valve member.
 4. The system of claim 3, wherein thestem and housing cooperatively define the variable orifice.
 5. Thesystem of claim 3, including a sleeve disposed between the stem and thehousing having an aperture therethrough in adjustable fluidcommunication with the fluid outlet of the outlet of the variableorifice assembly.
 6. The system of claim 3, including a conduit fluidlycoupled to the variable orifice assembly fluid outlet and extending tothe second chamber of the control pilot apparatus.
 7. The system ofclaim 2, wherein the at least one fluid conduit includes a first inletdisposed upstream of the main valve seat and in fluid communication withthe fixed orifice and the variable orifice assembly, and a second inletdisposed downstream of the main valve seat, the second inlet being influid communication with the first chamber of the pilot valve apparatus.8. The system of claim 3, including a pressure regulator apparatusdisposed between the fluid conduit inlet and the fluid inlet of thevariable orifice assembly, the pressure regulator apparatus comprising ahousing having a fluid inlet and a fluid outlet, and a selectivelyadjustable fluid passageway disposed between the inlet and outlet. 9.The system of claim 1, wherein the control pilot valve apparatusincludes a first flexible diaphragm attached to a movable yoke, and asecond flexible diaphragm attached to a movable stem and disposedbetween the first and second chambers, the stem and yoke movingindependent of one another and cooperatively forming a variable fluidpassageway between an inlet and outlet of the first chamber.
 10. Thesystem of claim 9, wherein the movement of the stem is adjustablylimited to a selected range defining a lower pressure set point, and themovement of the yoke is adjustably limited to a selected range definingan upper pressure set point.
 11. A method of controlling fluid flowthrough a main valve to maintain downstream pressure betweenpre-determined set points, comprising the steps of: generating a firstfluid stream having a pressure proportional to an inlet pressure of themain valve; passing a first portion of the first fluid stream through afixed orifice and through a variable fluid passageway and a firstchamber of a control pilot valve apparatus above a flexible diaphragmthereof, and into a main valve control chamber; passing a second portionof the first fluid stream through a variable orifice and into a secondchamber of the control pilot valve apparatus below the flexiblediaphragm; generating a second fluid stream having a pressureproportional to an outlet of the main valve, and placing the secondfluid stream in fluid communication with the first chamber of thecontrol pilot valve apparatus; detecting a pressure differential betweenthe first and second chambers of the control pilot valve apparatus; andhydraulically opening or closing the main valve in response to thedetected pressure differential by increasing or decreasing the fluidpressure into the control chamber of the main valve.
 12. The method ofclaim 11, including the step of automatically altering a fluidpassageway of the variable orifice in response to the opening andclosing of the main valve.
 13. The method of claim 11, including thestep of passing the second portion of the fluid stream through apressure regulator passageway before passing the second portion of thefluid stream through the variable orifice.
 14. The method of claim 13,including the step of adjusting the pressure regulator passageway inorder to modify a pressure regulation profile.
 15. The method of claim11, including the step of setting a lower pressure set point byselectively limiting a range of travel of the flexible diaphragm of thecontrol pilot valve apparatus.
 16. The method of claim 11, including thestep of setting an upper pressure set point by selectively limiting arange of travel of a second flexible diaphragm of the control pilotvalve apparatus disposed above the first chamber thereof.
 17. A variableorifice assembly, comprising: a valve having a fluid inlet and a fluidoutlet, a valve seat disposed between the inlet and the outlet, and avalve member movable between an open position away from the valve seatand a closed position engaging the valve seat; a housing associated withthe valve and defining a fluid inlet and a fluid outlet; and a stemconnected to the valve member and slidably disposed within the housing;wherein the movement of the stem within the housing creates a variablefluid orifice between the fluid inlet and the fluid outlet.
 18. Theassembly of claim 17, wherein the stem includes a fluid inlet in fluidcommunication with the fluid inlet of the housing, and a fluid outletvariably in fluid communication with the fluid outlet of the housingfrom a closed position to an open position as the stem is moved.
 19. Theassembly of claim 17, including a sleeve disposed between the housingand the stem, the sleeve having an aperture in fluid communication withthe housing fluid outlet, the stem adapted to variably permit fluid topass from the housing fluid inlet to the sleeve aperture.
 20. Theassembly of claim 19, wherein the sleeve is adjustably positioned withinthe housing to vary the fluid flow from the housing fluid inlet to thehousing fluid outlet.
 21. A control pilot valve apparatus, comprising: ahousing; a first flexible diaphragm disposed within the housing anddefining a first variable chamber above the first flexible diaphragm,the first variable chamber having a fluid inlet and a fluid outlet; amovable yoke attached to the first flexible diaphragm; a second flexiblediaphragm disposed within the housing in spaced relation to the firstflexible diaphragm and defining a second variable chamber below thesecond flexible diaphragm, the second variable chamber having a fluidinlet; and a stem slidably disposed relative to the yoke, and attachedto the second flexible diaphragm; wherein the yoke and the stem moveindependent of one another and cooperatively form a variable fluidpassageway between the inlet and the outlet of the first variablechamber.
 22. The apparatus of claim 21, wherein the stem includes anaperture variably alignable with a yoke aperture as the yoke and stemmove relative to one another to define the variable fluid passageway.23. The apparatus of claim 21, including an adjustable spring assemblyfor adjusting the movement of the yoke to a selected range defining anupper pressure set point.
 24. The apparatus of claim 21, including anadjustable spring assembly for adjusting the movement of the stem to aselected range defining a lower pressure set point.